The Ganga Geology - The Ganga: Water Use in the Indian Subcontinent - page 21

delta, was the main channel of the Ganga hardly 600 years ago and flowed, as it
does now, due south to the Saugar island, practically along the course of the present
Hooghly river. The main river appears to have frequently changed its course below
Gour in the last six centuries and successively discharged into the sea at different
mouths, such as Matla, Kalinai, Kabadakh and Haringhata in the Sunderbans.
Major Changes Since 16th Century
Early in the 16th century, the main course of the Ganga's shift eastward to the
present Padma may have been due to some tectonic changes and natural calami-
ties, leading to rapid deterioration of the Bhagirathi. At Bandel in Hooghly district,
the river bifurcated into the Saraswati and the Bhagirathi, alias Adi Ganga beside
and below Kolkata. The Saraswati (not to be confused with the unseen river of the
same name at Allahabad Sangam) was a major maritime river. A branch, ostensively
a man-made channel at Kolkata, connected it with the Bhagirathi/Adi Ganga. At that
time, the main course of the Damodar river used to flow into the main Bhagirathi at
a few kilometres north of Triveni. In 1770, following a severe flood, the Damodar
changed its course and flowed into the Bhagirathi, about 50 km south of Kolkata,
causing a major change in its system. Above the changed confluence point, the
Saraswati and the Bhagirathi became extinct and the Bhagirathi flowed along the
present course of the Hooghly. The remnant of the Adi Ganga is believed to be
the present Tolly's Nalla (Fig. 3.4).